Additionally, in patients with renal hypouricemia, extremely high FEUA (≥100%) is typical in renal hypouricemia type 2 (characterized by homozygous of non-functional GLUT9) but not in renal hypouricemia type 1 (characterized by homozygous of non-functional URAT1; typical FEUA, tens of %) (Kawamura et al., 2021). This evidence concerns the gene SLC22A12 and hypouricemia, renal.